Welcome back! To add to what @Fitik@fedia.io mentioned, there's also !mbinmeta@gehirneimer.de for discussion around Mbin and !mbinReleases@gehirneimer.de for posts about Mbin releases. If you want to get into the kbin.earth/interstellar ecosystem, there's also !kbinEarth (this magazine), !interstellar (for the Mbin app), and !interstellar_configs (for sharing Interstellar configurations).
If you'd really like to get into the history of what happened to kbin.social, try reading this post: https://lemmy.zip/post/20570491